The Role of Fog in the Hydrological Functioning of Tropical Island Ecosystems
Public Deposited- Last Modified
- March 20, 2019
- Creator
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Schmitt, Sarah
- Affiliation: College of Arts and Sciences, Department of Geography
- Abstract
- Fog is a critical water source in many tropical ecosystems, especially those that are semi-arid, or seasonally dry. Patterns of fog water input to these ecosystems are poorly understood, and currently limited by a lack of in-situ data spanning both space and time. Large gaps exist in our understanding of the spatiotemporal variability and mechanisms driving fog water deposition, and how fog travels through tropical systems. Given the significance of fog to semi-arid ecosystems across the globe, I use stable isotopes, remote sensing and plant physiological analyses to examine the role of fog in the semi-arid ecosystems of San Cristóbal Island, Galápagos and Ascension Island, UK by utilizing data from four field campaigns. I first create a ground-based optical fog detection scheme to trace fine-temporal scale mechanisms driving fog formation, evolution and dissipation across varying hydroclimatic zones. I then establish the isotopic signature of fog and other environmental waters to assess the overall contribution of fog to different microclimatic zones and under different hydroclimatic regimes. And finally, I trace fog through the Galápagos ecosystem, specifically examining how native versus invasive flora utilize fog under varying hydroclimatic conditions. In this research, I create a simple model to predict degree-of-fogginess with commonly measured meteorological variables, and I show how different fog formation mechanisms can be taking place in tandem over a concentrated spatial scale. I also demonstrate that fog is a common phenomenon on San Cristóbal Island, especially during the dry season, and that fog is consistently enriched compared to co-collected rainfall. Finally, I utilize the isotopic signature of fog and other environmental waters to trace water sources through the Galápagos ecosystem, suggesting that invasive guava’s water use strategy (including fog water utilization) plays a key role in its competitive capacity versus co-occurring native plants. Through this island lens, I address the critical disconnect between the hydrological and ecological role that fog plays in tropical island ecosystems. Taken together, these findings will be critical in projecting future water resource availability across many seasonally arid ecosystems, especially those that may become drier under future regimes of climate change.
- Date of publication
- December 2018
- Keyword
- DOI
- Resource type
- Rights statement
- In Copyright
- Advisor
- Moody, Aaron
- Hu, Jia
- Band, Lawrence
- Riveros-Iregui, Diego
- Song, Conghe
- Degree
- Doctor of Philosophy
- Degree granting institution
- University of North Carolina at Chapel Hill Graduate School
- Graduation year
- 2018
- Language
- Date uploaded
- January 4, 2019
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